Detecting and sorting means for sheets having flaws



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DETECTING AND Filed Dec. 10, 1965 CAMERA 8| AMPLIFIER FROM RESET 8 W.

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G. L. WATSON ET AL SORTING MEANS FOR SHEETS HAVING FLAWS 1" X D o g m KN I w I! "g N llN :0 HJ s V I1: (\I

.'I I II (0 N l l 0 II n l 2; H w I} "X I 5 Q? 3 II 1" INVENTORS GERALDL. WATSON DONALD L. STRADLEY ATTORNEYS United States Patent 3,389,789DETECTING AND SORTING MEANS FOR SHEETS HAVING FLAWS Gerald L. Watson,Portland, and Donald L. Stradley, Sherwood, 0reg., assignors to MooreVue, Inc., Portland, 0reg., a corporation of Oregon Filed Dec. 10, 1965,Ser. No. 512,874 8 Claims. (Cl. 20975) ABSTRACT OF THE DISCLOSURE A flawdetector for inspecting material such as, for example, wood products andthe like, includes a television camera for scanning across the materialas such material is moved relative to the camera on a conveyor. Thecamera produces an output indicative of flaws or imperfections therein,and the number of flaw indications is totaled in a counter. As pluralscans intersect the inspected material within a predetermined distancealong the material, indicating a flaw bridging such distance, anadditional value is added to the cumulative count. Plural actuatingmeans responsive to the counter classify the material according to flawcontent.

This invention relates to a flaw detector for use with products andparticularly to such a detector for automatically grading products.

Products such as panels of plywood, strips of veneer or the like, aregraded with respect to coloration flaws and defects. For certainpurposes, a strip of wood may be required having a minimum number ofknots or other color defects, while for certain other purposes a productwith a greater number of knots may be desired. In the case of woodpanels or strips, defective portions may be marked and cut out of thestrip after which the defective portion is replaced.

Some products such as particle board may be entirely rejected if theyinclude color defects which indicate an imperfection in the formation ofthe board. Other products may come through manufacture with an undulyrough surface, making an additional sanding operation desirable. In anycase, visual inspection of the material for location of such flaws andimperfections is not only time consuming and cumbersome, and thereforeexpensive, but, moreover, human inspection with the eye does not alwaysproduce uniform grading of the material.

It is therefore an object of the present invention to provide improvedautomatic apparatus for detecting flaws in material.

It is another object of the present invention to provide improvedapparatus for quickly and automatically grading and sorting material ina standardized manner not subject to human error and judgment.

In accordance with the present invention, a strip of material, which maycontain flaws or imperfections, is scanned optically with meansproducing an electrical signal, the amplitude of which is dependent uponlight reflection from the material being scanned. At the same time,relative movement is provided between the optical scanning means and thematerial being inspected so the entire surface of the material will beviewed. For example, a given electrical signal output level is producedwhen a standard wood finish is scanned, but a different level of signalresults if the scan passes a darker spot or discoloration such as a knotor the like.

A suitable scanning means comprises a television camera opticallyscanning the image of the strip of material, across the width thereof,producing a larger magnitude signal when a darker of discolored area isscanned. A level detector, receiving the output of the televisioncamera, is adjusted for providing an output only when 3,389,789 PatentedJune 25, 1968 "ice the video information from the television cameraexceeds a predetermined threshold value. Reflections associated with awood surface lacking iimperfections will not generate a televisioncamera output exceeding this value. When the camera scans a knot or thelike, the output rises above the threshold level of the level detectorand a level detector output occurs. This output of the level detectormay operate an actuator for marking or rejecting the imperfect material.Also a number of flaw indicating level detector outputs may be countedand the material graded accordingly.

In an embodiment according to the present invention, the scanning meansproduces a first repetitive scan across the moving material fordetecting flaws and producing an output when an imperfection isdetected. When an imperfection is detected a second scan, parallel tothe first scan, is employed for determining whether or not the detectedflaw spans the spacing between the two scans. If it does, the materialmay either be rejected, or the additional detection added in a counterto the original flaw detection, thereby downgrading material havingimperfections larger than a predetermined spacing between scans.

According to another embodiment of the present invention, the scanningapparatus is effective in rejecting material on account of surfaceroughness. The material is illuminated with polarized light and apolarizer for detecting such light is placed between the scanning meansand the material. Roughness 0n the surface of the material changes theamount of light reflected to the scanning means causing a change in theoutput signal of the scanning means.

The subject matter which we regard as our invention is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. The invention, both as to organization and method ofoperation, together with further advantages and objects thereof may bestbe understood by reference to the following description taken inconnection with the accompanying drawings wherein like referencecharacters refer to like elements in which:

FIG. 1 is a schematic diagram of a first circuit in accordance with thepresent invention,

FIG. 2 is a chart of waveforms illustrating the operation of the FIG. 1circuit,

FIG. 3 is a schematic diagram of another embodiment of the presentinvention,

FIG. 4 is a diagram of a television raster which may be employed inconjunction with the present invention,

FIG. 5 is a view of a first mechanical transducer which maybe employedwith the FIG. 3 circuit, and

FIG. 6 is a view of a second mechanical transducer which may be employedwith the FIG. 3 circuit.

Referring to FIG. 1, illustrating a first circuit in accordance with thepresent invention, a television camera 10 is positioned to view a stripof wood material 14 supported for movement on a conveyor belt 16.Conveyor belt 16 is arranged to move wood material 14 past the camera 10in a direction perpendicular to the drawing and lengthwise of thematerial. Camera 10, in this embodiment, is a conventional televisioncamera having an associated amplifier and producing one or more linescans across the wood material 14, or the image thereof, in a direction18 across the material 14 from one side thereof to the other. The scanis rapidly repeated and may form one scan of a conventional televisionraster of 525 scan lines with the lines disposed in a directioncrosswise of the material 14. The video information corresponding to theone or more scan lines is provided at output 20 and this output isportrayed in the FIG. 2 waveform chart. This output sign-a1 comprisessynchronization pulses 22 including a horizontal blanking pulse andhorizontal sync pulse as well as video information located between thesynchronization pulses. As the camera executes a scan in a directionperpendicular to the movement of material 14, a light colored or graybackground 24 will be indicated at either side of the video informationbetween the video information 26 and the synchronization pulses 22. Thevideo signal 26 remains at a relatively constant level for each scanproviding no imperfection is viewed, that is providing the lightreflected to the television camera is from the ordinary wood surfacecontaining no major flaws. Movement of the wood material 14 on conveyerbelt 16, relative to television camera 10, positions the material sothat a given scan of the televesion raster produces successive videoinformation for slightly displaced areas of the wood material surface tothe end that the entire surface of the wood material 14 is inspected.One or more scans for each raster, or even the entire raster, may beemployed if so desired. The material is appropriately illuminated bymeans not shown so as to be visible to the television camera.

The instantaneous output of camera 10 is applied as an input to leveldetector 28. This level detector produces no output as long as the videoinformation 26 has a relatively constant value indicative of a surfacehaving no appreciable imperfection. However, when a knot or other flawis scanned by the television camera, a peak 30 in the video informationwill occur, as seen in FIG. 2, because the flaw is darker in color thanthe surrounding wood surface. The peak 30 in this instance is notsufficient to operate the level detector 28 since it does not exceedthreshold level 32. However, a succeeding scan of a further portion ofthe same flaw produces a peak 38a reaching threshold level 32 of leveldetector 28, causing the production of an output therefrom. Likewise,peak 301) similarly produces an output from level detector 28.

The level detector 28 is suitably a Schmitt trigger circuit having athreshold level 32 at which a continuous output is produced, and asecond threshold 34 at which time the output of the circuit isdiscontinued. The range between threshold levels 32 and 34 is called thehysteresis range of the Schmitt circuit. When an input signal applied tothe Schmitt circuit exceeds threshold level 32 and then continues toexceed this level or remains within the hysteresis range, a continuousoutput is produced. Although the Schmitt trigger circuit is quiteefiicacious for producing suitable waveforms for operating thesubsequent circuitry as hereinafter more fully described, other devicesfor providing an output when the device input exceeds a particular valueare also usable.

The output 31 of the Schmitt trigger level detector 28 in the FIG. 1embodiment is applied to a first monostable circuit 33 and also to and-gate 35. The monost-able circuit 33 may suitably comprise a one-shotmultivibrator. Application of output 31 to monostable circuit 33 causesthe latter to generatea 11 output 36 for a predeermined length of time,starting at the conclusion of the output 31 from level detector 28.Similarly the output of monostable circuit 33 triggers a secondmonostable circuit 38 having an output 40 persisting for a predeterminedperiod of time after the conclusion of the output 36 from monostablecircuit 33. Output 40 is applied in conjunction with output 31 toand-gate 35, the latter producing an output labeled 42 only uponcoincidence of 31 and 40. This coincident output 42 triggers bistableflip-flop 44 and causes its operation to change from a first state to asecond or output producing state. The output of flip-flop 44 is labeled46. This output drives actuator 48, which may comprise a marker, anindicator, or suit-able relay means for causing rejection of a strip ofwood material containing a flaw exceeding the predetermined standard. Asingle such actuator is suitable, for example, for use in the case wherethe material 14 is particle board and wherein detection of a flaw isdesired to cause rejection of the material.

The FIG. 1 circuit beyond level detector 28 performs the function ofproviding an enabling gate signal only while video information occurs inoutput of television camera 10. This gate signal is the output 40 ofmonostable circuit 338. When camera 10 produces a synchronization pulse22, the synchronization pulse will exceed the hysteresis range ofSchrnitt trigger level detector 28, thereby producing an output 31 fortriggering monostable circuit 33 at the end of the output 31. The output36 of monostable circuit 33 is arranged to be 'a pulse having arelatively short duration concluding while the gray background is beingscanned and before the edge of the material 14 is reached by the scan.At the conclusion of output 36 of monostable circuit 33, the monostablecircuit 38 is triggered, producing gate signal output 40 which continuesduring the presence of video signal 26 until the scan reaches the grayarea at the other side of material 14 and before the occurrence of thenext synchronization pulse 22.

Since output 40 of monostable circuit 28 and output 32 of level detector28 are both applied to and-gate 35, both must be present to operate theand-gate. The output pulses 31 of level detector 28 coincident withsynchronization pulses 22 will not produce an output 42 at andgate 35.However, when peak 36a occurs in the video signal, indicating a flaw inthe material being scanned, the output 31 of level detector 28 iscoincident with gate signal output 40, and bistable flip-flop 44 istriggered, producing continuous output 45 indicative of the flaw in thematerial scanned.

Bistable flip-flop circuit 44 comprises a storage means storing therecognition of a flaw in material 14 until the circuit is reset viagrounding lead 59 in a conventional manner. This is convenientlyaccomplished through a microswitch (not shown) connected to lead andclosed by the trailing edge of material 14 passing over such switch toconnect lead 50 to ground.

Although a conventional television camera is illustrated and is verydesirable from the standpoint of producing accurate signals whiledisregarding unwanted light input, other optical scanning means may besubstituted therefor. For example, a flying spot scanner and suitablesynchronization circuitry can be used in place of television camera 10.

Referring to FIG. 3 illustrating another embodiment of the presentinvention, a television camera 10 scans across the strip of material 14such as plywood or veneer conveyed on a moving belt 16. The material 14is illuminated by light source 52 directed towards the material 14through lens 54. The light also passes through a first polarizer 56,before striking the material 14, for polarizing the light in a directioncrosswise of material 14 and parallel to the scanning direction oftelevision camera 10. The light is reflected from the material 14 andfrom mirror 58, and passes through a second polarizer to the televisioncamera. Polarizer 60 is oriented in a direction for normally passing thepolarized light reflected from a standard surface of material 14. Thatis, polarizer 60 is oriented along substantially the same optical axisas polarizer 56.

Scanning of television camera 10 executes a raster as illustrated inFIG. 4 composed of parallel closely spaced horizontal scans. The thirdand the fifteenth horizontal scans are indicated. The video output fromtelevision camera It) is applied to and-gate 62 in FIG. 3, whilehorizontal and vertical triggering signals synchronized with thehorizontal and vertical synchronization pulses from the televisioncamera are applied to counter 64. These triggering signals areconveniently derived in the television camera by differentiating thehorizontal and vertical fiyback voltages respectively. The verticaltriggering signal from television camera 10, applied via lead 66, startscounting operation in counter 64. Counter 64 then counts the number ofhorizontal triggering pulses applied via lead 68, and the count thereofthus indicates the number of the scan being executed by televisioncamera 10. When counter 54 reaches a predetermined number, for examplerepresenting the fifteenth scan, as illustrated in FIG. 4, the counter64 produces an output 72 for application to pulse generator 74. Pulsegenerator 74 generates a gate signal output 76 which is introduced as anenabling input to and-gate 62. And-gate 62 therefore passes videoinformation for the particular scan, i.e., the fifteenth scan of thetelevision raster.

The output 78 of and-gate 62 is selectably connected to A level detector80 through switch 81. When the output of the television camera reaches apredetermined level, the A level detector 80 generates an output at lead82 which is applied to a counter 84. Counter 84 counts the number oftimes the video output exceeds the predetermined level of level detector80. Therefore, the count in counter 84 is a measure of the grade orquality of the material viewed by the television camera.

Additional circuitry is then actuated beyond counter 84 in accordancewith the number of flaws found in the material. Providing counter 84contains a predetermined minimum count, actuator 86 is energized throughpass A gate 88. However, if the counter contains a larger countindicating a greater number of imperfections, actuator 90 is energizedfrom a second output of counter 84 through rework 1 gate 92 and thelatter is connected to inhibit pass A gate 88 through inhibit lead 94. Ayet greater count from counter 84 provides an output energizing actuator96 through rework 2 gate 98, the latter inhibiting rework 1 gate 92 viainhibit line 100. Inhibit lines 94 and 100 prevent more than oneactuator from being energized at a particular time.

Actuators 85, 9G, and 96 may comprise relays or other devices of asimilar type for initiating a particular sorting operation of material14. For example, if a strip of material 14 contains a certainpredetermined minimum number of flaws resulting in a minimum count incounter 84, actuator 86 will be energized and permit the strip ofmaterial 14 to pass on the conveyor belt 16, resulting in a grade Aclassification of material. However, when actuator 90 is energized, itcauses the strip being viewed by the television camera to be marked orrejected into a rework classification. Similarly, actuator 96- rejects astrip of material in a second rework classification.

A second level detector, 8012, with counter 84b and associatedclassification circuitry, is selectable with switch 4.)

81 whereby output 78 of and-gate 62 is connected to level detector 80b.The classification circuitry associated with level detector 80b andcounter 84b is substantially identical to that discussed above except anadditional actuator 102/5 is included and the latter is adapted to beenergized from a predetermined count of counter 84b through upgrade to Agate 104b. Gate 104!) also receives an inhibit signal on lead 10612 frompass B gate 8815, should the latter be energized.

The circuit including level detector 8%, counter 84b, and associatedcircuitry may be used for further classification of a strip of material14 after the strip has received classification through the use of leveldetector 80, counter 84, and associated circuitry. If, for example,actuator 96 rejects a strip of material as being in a rework 2 category,this strip may then be rerun through the same or a similar system havingswitch 81 in the position selecting level detector 80b. Counter 84b isarranged to energize actuator 86!), providing the strip meets a pass Ifthe material after rechecking appears to contain a lesser number offlaws, actuator 102!) will be energized and the strip returned forhigher level classification.

With the switch 81 in either of the aforementioned positions, actuators90 and 98b, respectively, classify the strip of material forreinspection with switch 81 remaining in the same position in the rerun.If, on the other hand, either actuator 96 or 96b is energized, the stripof material is classified for a lower level of inspection. For example,energization of actuator 96 classifies the strip of material beinginspected for a reintroduction into the system with switch 81 selectinglevel detector 8012.

In the third position of switch 81, a level detector c is selected. Theoutput 82c is connected to a counter 84c, suitably provided withclassification circuitry for further classifying the strip of materialbeing inspected.

Although one system employing switch 81 is shown for inspecting thematerial 14, it is understood a plurality of such systems including aplurality of television cameras may be suitably positioned along aconveying system arranged for moving and classifying the strip material.Moreover, a strip of material may be conveniently classified into acategory within predetermined limits employing more than one circuit ofa FIG. 3 type. For example, two such circuits may be arranged with theirtelevision cameras arranged successively along conveyor belt 16, or witha television camera for one circuit arranged on one side of the movingmaterial and another television camera disposed on the remaining side.It may be desired to accept material passing both B and C criteria whilerejecting others. Then, one circuit of the FIG. 3 type may be arrangedwith switch 81 in a position to select B level detector 89b, and asecond such circuit may be arranged to have its switch 81 in a positionfor selecting C level detector 800. In the operation of such a system, astrip of material will be passed if either actuator 86 of the firstcircuit or actuator 86b of the second circuit is energized. Many othercombinations are possible, of course.

Counter 64 also produces an output 108 when it reaches a count eithersomewhat earlier or somewhat later than the count which produced output72. In a particular example, counter 64 produces an output 108 when thetelevision camera 10 reaches its third scan across material 14 asillustrated on raster 70 in FIG. 4. Output 108 is applied to early lookgate 110. Early look gate 110 receives a signal from one of the leveldetectors 80, 80b, 80c, etc., according to the position of switch ,112which is ganged with switch 81 so that the same level detector isincluded in the circuit by both switches 81 and 112. When level detector80, for example, produces an output 82 indicating a flaw in the materialbeing inspected, a delayed output 114 therefrom is applied to early lookgate 110 through switch 112. Gate 110 then passes output 108 of counter64 through gate 110 supplying an input 113 to pulse generator 74 duringthe third scan of the next television raster, the third and thefifteenth scans of the raster being parallel to each other and spaced bya predetermined distance. The output of pulse generator 74 gates thevideo information not only for the fifteenth such scan but also for thethird scan during the next raster time. This provision of videoinformation from an additional scan line path parallel to the first scanline path, for example, from the third scan line parallel to the usualfifteenth scan line, is used to detect flaws in material 14 of a sizespanning the distance between the scan lines on the image of the flaw.Then, should a flaw span this distance, an additional count will be'added to the selected counter 84, 84b, 84c, etc. Therefore, a greaterchance of rejection exists in the case of flaws having a size spanningthe distance. Of course, the size involved can be selected by adjustingcounter 64 to produce an output 108 at the time of a scan closer to, orfurther away from, the

usual scan out tit 72 rovided b uls t B criteria involving apredetermined number of flaws. 00 P p y p e genera or 74 It isunderstood that polarizers 56 and 60 are not necessary in detectingflaws in the material 14 detectable by color alone. That is, flaws of adarker color, for example, a knot or the like in material 14, willregister at a properly adjusted level detector without the use ofpolarized light. Polarized light employing the polarizers 56 and 60 isuseful in detecting undue roughness on the surface of material 14. Forthis purpose, the light is presented at the surface of material 14 at anangle of approximately 37 degrees with respect to the vertical. A mirror58 is arranged to reflect the reflection from material 14 to thetelevision camera 10 through polarizer 60 oriented for passing thepolarized light. However, should the material 14 have an unduly roughsurface, the polarized light will be dispersed and television camera 16will receive less light and produce a signal as in the case of a darkspot. Of course, the system may be arranged for the detection ofdispersed light from a rough spot by readjusting the angle and positionof mirror 58. The use of polarized light for detecting roughness may beapplied as well to the FIG. 1 apparatus.

FIGS. 4 and 5 illustrate mechanical transducers which may be employed inconjunction with the circuit of FIG. 3. Each of these transducersincludes a pivoted arm 114 carrying serrated wheel or disk 116 which maybe formed of plastic or the like, for physically contacting the surfaceof moving material 14. Each transducer arm includes a movable contact118 of a switch 120 also having a stationary contact 122. When theserrated wheel passes over a rough spot, the contact 118 of switch 120moves towards contact 122 making connection therewith. The switch 120may be included in the FIG. 3 circuit, as indicated in FIG. 3, forbriefly connecting a DC source 124 to level detector 80. A plurality ofsuch transducers disposed across the surface of moving material 14 willcause the addition of one or more brief inputs to level detector 80 viaone of the switches 120, thereby providing an additional count incounter 84 indicative of physical roughness on the surface of material 13.

The apparatus according to the present invention provides automaticmeans for detecting flaws and imperfections in material and suitablerejection or classification of the material according to the presence ofsuch fiaws. This operation is carried on automatically and Without theneed of extensive and time-consuming human sorting, subject to errors inhuman judgment.

While we have shown and described several embodiments of our invention,it will be apparent to those skilled in the art that many changes andmodifications may be made without departing from our invention in itsbroader aspects. We intend the appended claims to cover all such changesand modifications as fall within the true spirit and scope of ourinvention.

I claim:

1. Apparatus for detecting flaws in material comprising means for movinga sheet of material past a given oint in a given direction,

television camera means scanning across an image of said material in adirection substantially across the direction of movement of saidmaterial and producing an instantaneous electrical output indicative oflight from said material,

detector means responsive to the output of said television camera meanswhen the output of said telesion camera means changes to a valueindicating light from an imperfection in said material,

and means for providing a further response in said apparatus when firstand second scans across the image of said material, within apredetermined distance therealong in the direction of movement thereof,indicate imperfections in said material bridging said first and secondscans.

2. Apparatus for detecting flaws in material comprising means for movingsaid sheet of said material past a given point in a given direction,

television camera means scanning across an image of said material in adirection substantially across the direction of movement of saidmaterial and producing an instantaneous electrical output indicative oflight from said material,

level detector means responsive to the output of said television camerameans for producing an output thereof when the output of said televisioncamera means substantially changes from a value indicating light fromacceptable material to a value produced by light from an imperfection insaid material,

said television camera means providing a first repeti' tive scan in adirection across said image of said material in a first given path, andmeans responsive to an output of said level detector means for applyinga signal from said television camera means corresponding to a secondpath substantially parallel to said first path but spaced therefrom asan additional input to said level indicator means for exceeding thelevel thereof When the scan of said second path intersects an image of afiaw extending at least the distance of the spacing between said firstand second paths. 3. Apparatus for indicating flaws in materialcomprising means for moving a sheet of said material past a given pointin a given direction,

television camera means scanning across an image of said material in adirection substantially across the direction of movement of saidmaterial and producing an instantaneous electrical output indicative oflight from said material, detector means responsive to the output ofsaid television camera means for producing an output when the output ofsaid television camera means changes to a value indicating animperfection in said material, a light source directed towards saidmaterial, light polarizer means positioned in a light path between saidlight source and said material and oriented to polarize the lightthereof in a direction across said material and substantially parallelwith the scanning direction of said television camera means,

and second light polarizer means for receiving polarized reflection fromsaid material, said second light polarizer means being located betweensaid material and said television camera means and also being orientedfor polarization of light in a direction across said material andparallel to said scanning direction of said television camera means,said television camera means producing an output signal for applicationto said detector means having an amplitude indicative of the roughnessof the material being scanned, said roughness causing dispersion of thepolarized light between said light polarizer means. 4. Apparatus fordetecting flaws in material comprising means for moving a sheet of saidmaterial past a given point in a given direction,

television camera means scanning across an image of said material in adirection substantially across the direction of movement of saidmaterial and producing an instantaneous electrical output indicative oflight from said material, detector means responsive to the output ofsaid television camera means for producing an output thereof when theoutput of said television camera means significantly changes from avalue indicating light from acceptable material to a value produced bylight from an imperfection in said material,

counter means for substantially totaling the number of outputs from saiddetector means,

and a plurality of actuator means, each responsive to a difierent countof said counter means for classifying said material for the purpose ofgrading said material according to flaw content.

5. Apparatus for detecting flaws in material comprising:

means for continually movin strips of material in a direction lengthwiseof said strips,

television camera means for line scanning across each strip of materialfrom one side to the other across the direction of movement thereof andproducing an electrical signal varying in amplitude in accordance withthe light reflection of said strip of material as well as horizontalsynchronization pulses at the end of each scan,

level detector means for producing an output when the amplitude of thesignal from said television camera means exceeds a predetermined value,

gate means responsive to said level detector means for producing a gatesignal during the occurrence of the line scan across the width of saidmaterial but not during the occurrence of said synchronization pulses,

means responsive to the simultaneous presence of an output from saidlevel detector means and from said gate means, and

storage means operated by said means responsive to said simultaneouspresence when said gate signal and said output of said level detectormeans occur simultaneously for giving a stored indication of a flaw insaid material.

6. Apparatus for detecting flaws in material comprising:

means for providing movement of a strip of material in a direction alongits length,

a light source directed toward said material,

television camera means for scanning across said strip of material fromone side thereof to the other for producing an output whose value variesinstantaneously in accordance with the light reflected to saidtelevision camera tube from said material,

successive scans of said television camera tube producing a raster ofparallel scans with each displaced from the previous scan by apredetermined amount,

first counter means for counting the number of scans and producing anoutput when a particular numbered first scan is reached,

gate means operated by said first counter means for gating the videosignal of said television camera, the amplitude of which varies inaccordance with the reflection of light from said material during aparticular scan,

level detector means responsive to such gated output when said outputreaches a predetermined level,

second counter means receiving the output of said level detector anditself producing an output when the number of outputs of said leveldetector reaches a predetermined value,

plural actuator means responsive to different counts of said secondcounter means for classifying and sorting said material, and

gate means between said second. counter means and various of saidactuator means including inhibiting connections for preventing more thanone said actuator means from being responsive at a particular time.

7. The apparatus according to claim 6 further including means forreceiving the count of said first counter means and producing an outputwhen said first counter means produces an output indicative of a scandifierent from said first mentioned scan,

said further means being responsive to an output of said level detectormeans when a flaw is detected to cause application of video informationoccurring during a said second scan in a raster succeeding a first scanwhen a flaw is detected to add said video information as an input tosaid level detector means.

8. The apparatus according to claim 6 further including mechanicaltransducers contacting said material and producing an additional countin said second counter means when a said mechanical transducer detectsroughness on the surface of said material.

References Cited UNITED STATES PATENTS 2,735,017 2/1956 Beard et a1209-1117 2,947,212 8/1960 Woods 250 2'25 X 2,975,293 3/1961 Kruse of al250-219 3,019,346 1/1962 Laycak 235-92 3,096,443 7/1963 Laycak 250-2193,264,480 8/1966 Zuck er a1 250-219 ALLEN N, KNOWLES, Primary Examiner,

